Carter rebuild kit?

Tuning is pretty easy actually, just like a modern Edelbrock. In fact, edelbrock bought Carter, so you can use Edelbrock jets and needles for tuning. Only thing is that you can't use an edelbrock top gasket, for some reason it has a larger hole around the floats that causes an air leak on the Carter. But the AFB's are pretty much just edelbrock performers, the Carter AVS's are just like the Thunder AVS series.

I just finished tuning a Carter Competition AFB 625 for my 318, its pretty easy once you get the hang of it.

I wouldn't paint it, not likely to stay put given that its a carburator and will be exposed to high heat and fuel. Its aluminum, so you could polish it if you were really ambitious, otherwise I'd just scrub it down with some carb cleaner.